An analysis of four foundational issues in the study of moral development is provided. The four issues involve: (1) the definition of morality; (2) individual or cultural moral variation; (3) moral ontogeny; and (4) moral epistemology. The first section of the paper describes each issue. The second section is based on the argument that the four issues can be combined in six paired combinations, four of which often result in confusions or conflations in the theoretical and empirical research literature. Each of the four problematic combinations is discussed. It is suggested that while the content of moral-developmental controversies can vary widely, the sources of the controversies are often bounded by one or more of the four issues under consideration. Examples are offered of ways in which moral theory and research have confused evidence that pertains to two or more of the issues. While these issues are analytically distinct, they often can and should be brought together in moral theory and research. Approximately 75 references are cited. (RH)